Dissecting the Mechanisms Underlying the Cytokine Release Syndrome (CRS) Mediated by T-Cell Bispecific Antibodies

PURPOSE

Target-dependent TCB activity can result in the strong and systemic release of cytokines that may develop into cytokine release syndrome (CRS), highlighting the need to understand and prevent this complex clinical syndrome.

EXPERIMENTAL DESIGN

We explored the cellular and molecular players involved in TCB-mediated cytokine release by single-cell RNA-sequencing of whole blood treated with CD20-TCB together with bulk RNA-sequencing of endothelial cells exposed to TCB-induced cytokine release. We used the in vitro whole blood assay and an in vivo DLBCL model in immunocompetent humanized mice to assess the effects of dexamethasone, anti-TNFα, anti-IL6R, anti-IL1R, and inflammasome inhibition, on TCB-mediated cytokine release and antitumor activity.

RESULTS

Activated T cells release TNFα, IFNγ, IL2, IL8, and MIP-1β, which rapidly activate monocytes, neutrophils, DCs, and NKs along with surrounding T cells to amplify the cascade further, leading to TNFα, IL8, IL6, IL1β, MCP-1, MIP-1α, MIP-1β, and IP-10 release. Endothelial cells contribute to IL6 and IL1β release and at the same time release several chemokines (MCP-1, IP-10, MIP-1α, and MIP-1β). Dexamethasone and TNFα blockade efficiently reduced CD20-TCB-mediated cytokine release whereas IL6R blockade, inflammasome inhibition, and IL1R blockade induced a less pronounced effect. Dexamethasone, IL6R blockade, IL1R blockade, and the inflammasome inhibitor did not interfere with CD20-TCB activity, in contrast to TNFα blockade, which partially inhibited antitumor activity.

CONCLUSIONS

Our work sheds new light on the cellular and molecular players involved in cytokine release driven by TCBs and provides a rationale for the prevention of CRS in patients treated with TCBs. See related commentary by Luri-Rey et al., p. 4320.

Cross-linking of T cell to B cell lymphoma by the T cell bispecific antibody CD20-TCB induces IFNγ/CXCL10-dependent peripheral T cell recruitment in humanized murine model

Diffuse large B cell lymphomas (DLBCL) are a highly heterogeneous subtype of Non Hodgkin Lymphoma (NHL), accounting for about 25% of NHL. Despite an increased progression-free survival upon therapy, 40-50% of patients develop relapse/refractory disease, therefore there remains an important medical need. T cell recruiting therapies, such as the CD20xCD3 T cell bi-specific antibody CD20-TCB (RG6026 or glofitamab), represent a novel approach to target all stages of DLBCL, especially those that fail to respond to multiple lines of treatment. We aimed for a better understanding of the molecular features related to the mode of action (MoA) of CD20-TCB in inducing Target/T cell synapse formation and human T cell recruitment to the tumor. To directly evaluate the correlation between synapse, cytokine production and anti-tumor efficacy using CD20-TCB, we developed an innovative preclinical human DLBCL in vivo model that allowed tracking in vivo human T cell dynamics by multiphoton intravital microscopy (MP-IVM). By ex vivo and in vivo approaches, we revealed that CD20-TCB is inducing strong and stable synapses between human T cell and tumor cells, which are dependent on the dose of CD20-TCB and on LFA-1 activity but not on FAS-L. Moreover, despite CD20-TCB being a large molecule (194.342 kDa), we observed that intra-tumor CD20-TCB-mediated human T cell-tumor cell synapses occur within 1 hour upon CD20-TCB administration. These tight interactions, observed for at least 72 hours post TCB administration, result in tumor cell cytotoxicity, resident T cell proliferation and peripheral blood T cell recruitment into tumor. By blocking the IFNγ-CXCL10 axis, the recruitment of peripheral T cells was abrogated, partially affecting the efficacy of CD20-TCB treatment which rely only on resident T cell proliferation. Altogether these data reveal that CD20-TCB's anti-tumor activity relies on a triple effect: i) fast formation of stable T cell-tumor cell synapses which induce tumor cytotoxicity and cytokine production, ii) resident T cell proliferation and iii) recruitment of fresh peripheral T cells to the tumor core to allow a positive enhancement of the anti-tumor effect.

Abstract 4229: Anti-P329G-CAR-T cells as a novel universal CAR-T cell platform

Introduction: In the rapidly growing field of chimeric antigen receptor (CAR) engineered T cells new approaches aim to make CAR-T cell therapy safer and more effective. Recent, designs aim towards universal or modular CARs that do not directly recognize the target antigen itself, but instead facilitate contact to CAR-adaptor molecules, which in turn bind to the target antigen. Current CAR-adaptor molecules include human antibodies of the IgG1 isotype binding to CD16 or antibodies modified by peptide or hapten tags. We developed a modular CAR-T approach that recognizes the P329G mutation clinically used to silence the Fc effector function of therapeutic antibodies. These modular anti-P329G-CAR-T cells are only functional in the presence of antibodies that possess the P329G mutation.

Methods: The anti-P329G interaction with P329G-containing Fc fragment was analyzed using surface plasmon resonance and co-crystallography. Lentivirus transfected anti-P329G CAR-T cells were characterized in vitro for their selectivity and potential to mediate antigen specific tumor cell lysis, cytokine secretion and proliferation. Immunological synapse formation was investigated using confocal microscopy.

Results: Anti-P329G-CAR-T cells allow the precise recognition of the P329G mutation present in therapeutic IgG1 based adaptor-molecules. Crystal structure- and SPR-analysis revealed a 1:1 binding stoichiometry with low nanomolar affinity of the P329G-Fab fragment applied in the CAR for P329G-containing IgG1 antibodies. Potent tumor cell lysis was demonstrated for multiple tumor antigens e.g. CD20, HER2, FOLR1, EpCAM, FAP and others. For all tested antigens, a huIgG1 dose-dependent activation of anti-P329G-CAR-T cells as well as dose-dependent tumor cell lysis was observed. For selected antigens P329G-CAR-T activity was found comparable to the activity mediated by T cell bispecific antibodies recognizing the respective tumor antigen. Finally, the immunological synapse formed by P329-CAR-T cells was compared to the one formed by T cell bispecific antibodies in a 2+1 format.

Conclusions: P329G-CAR-T cells mediate potent and specific tumor cell killing using various tumor targeted antibodies as adaptor molecules. Based on these data in vivo studies to investigate efficacy and safety of the approach are foreseen. Notably, this approach allows control of CAR-T activity and potential side effects by titrating the adaptor molecule, as well as the simultaneous targeting of more than one antigen at the same time with the goal to prevent tumor escape mechanisms. Combining the P329G-CAR with allogenic T-cells may provide a truly off-the-shelf P329G-CAR-T cell therapy approach.

Citation Format: Diana Darowski, Christian Jost, Zeno Riester, Mohamed Benmebarek, Kay Stubenrauch, Anne Freimoser-Grundschober, Uwe Wessels, Jörg Benz, Ekkehard Mössner, Renier Myburgh, Floriana Cremasco, Mario Perro, Pablo Umana, Sebastian Kobold, Christian Klein. Anti-P329G-CAR-T cells as a novel universal CAR-T cell platform [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4229.

Autophagy mediates epithelial cancer chemoresistance by reducing p62/SQSTM1 accumulation

To cope with intrinsic and environmental stress, cancer cells rely on adaptive pathways more than non-transformed counterparts. Such non-oncogene addiction offers new therapeutic targets and strategies to overcome chemoresistance. In an attempt to study the role of adaptive pathways in acquired drug resistance in carcinoma cells, we devised a model of in vitro conditioning to three standard chemotherapeutic agents, cisplatin, 5-fluorouracil, and docetaxel, from the epithelial cancer cell line, HEp-2, and investigated the mechanisms underlying reduced drug sensitivity. We found that triple-resistant cells suffered from higher levels of oxidative stress, and showed heightened anti-stress responses, including the antioxidant Nrf2 pathway and autophagy, a conserved pleiotropic homeostatic strategy, mediating the clearance of aggregates marked by the adapter p62/SQSTM1. As a result, re-administration of chemotherapeutic agents failed to induce further accumulation of reactive oxygen species and p62. Moreover, autophagy proved responsible for chemoresistance through the avoidance of p62 accumulation into toxic protein aggregates. Indeed, p62 ablation was sufficient to confer resistance in parental cells, and genetic and pharmacological autophagic inhibition restored drug sensitivity in resistant cells in a p62-dependent manner. Finally, exogenous expression of mutant p62 lacking the ubiquitin- and LC3-binding domains, required for autophagic engulfment, increased chemosensitivity in TDR HEp-2 cells. Altogether, these findings offer a cellular system to investigate the bases of acquired chemoresistance of epithelial cancers and encourage challenging the prognostic and antineoplastic therapeutic potential of p62 toxicity.

Abstract 5413: Multiplexed phosphoprotein cell signaling analysis in multiple myeloma reveals a pro-survival pathway elicited by amino-acid starvation

Background: Substantial advances in our understanding of the biology of the incurable plasma cell (PC) malignancy multiple myeloma (MM) came from the study of the bone marrow (BM) microenvironment (BMME). Our previous work disclosed an essential role for autophagy in sustaining MM cell proliferation and survival. However, the control exerted on PC autophagy by the BMME and its pathophysiological significance are virtually unknown.

Experimental design: We integrated ex vivo multiplexed phosphoprotein cell signaling analyses of primary MM and BMME cells, metabolomic profiling of patient-derived BM and peripheral plasma, and in vitro studies on human MM cell lines. Primary CD138+ MM and BMME CD138- cells were isolated from BM aspirates obtained from 35 clinically characterized MM patients and 60 proteins - representative of autophagy, cell survival, proliferation, protein degradation and translation pathways - were analyzed by Reverse Phase Protein Arrays (RPPA).Comprehensive metabolomics profiling was achieved by ultra-high performance liquid and gas chromatography followed by mass spectrometry (UHPLC/GC-MS) on ad hoc-collected B and peripheral plasma samples from patients at different disease stages (30 MGUS, 17 smoldering MM, 16 MM) and age-matched healthy donors (29). For in vitro studies, human MM lines were exposed to amino acid (AA) depletion and selected responses evaluated by quantitative RT-PCR and immunoblotting analyses.

Results: First, RPPA revealed that patients with the most aggressive clinical presentation (refractoriness, short time to progression and active bone disease) displayed higher activity of the PI3K/AKT/mTOR pathway associated to higher expression of the autophagic proteins ATG5, LC3B and p62. In search for extrinsic stimuli capable of raising both mTOR and autophagic activity, we recapitulated such expression pattern in MM cells through selective starvation of tryptophan (Trp) and arginine (Arg), two AA endowed with distinctive immune regulatory activity. When exposed to Trp-free or Arg-free medium, human MM cell lines activated GCN2-mediated responses, increasing mTOR, p-S6RP, CHOP, p62 and Blimp-1 and immunoglobulin secretion; conversely, stable lentiviral p62 silencing reduced Blimp-1 and caused the in vitro extinction of MM cell lines within 10 days of culture. UHPLC/GC-MS metabolomics analysis of plasma samples revealed a progressively and significantly lower concentration of Trp and Arg associated with disease evolution and shorter progression-free survival.

Conclusion: Taken together, our findings disclose a novel extrinsic circuit whereby reduced concentration of the essential immunoregulatory AA Trp and Arg sustains PC cell fitness and survival. Attesting to pathophysiologic relevance, this mechanism appears coopted by MM as a component of its vicious BMME.

Note: This abstract was not presented at the meeting.

Citation Format: Alessandra Romano, Floriana Cremasco, Antonella Chiechi, Francesca Paradiso, Enrico Milan, Francesca Fontana, Jose M. Manteiga, Francesco Di Raimondo, Alexander I. Spira, Amy Van Meter, Emanuel Chip Petricoin, Virginia Espina, Lance A. Liotta, Simone Cenci. Multiplexed phosphoprotein cell signaling analysis in multiple myeloma reveals a pro-survival pathway elicited by amino-acid starvation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5413. doi:10.1158/1538-7445.AM2017-5413

B cell homeostasis and follicle confines are governed by fibroblastic reticular cells

Naive B and T cells exist in discrete zones in lymph nodes. Turley and colleagues demonstrate that a distinct subset of fibroblastic reticular cells reside in B cell zones, where they sustain B cell survival by providing BAFF.

Fibroblastic reticular cells (FRCs) are known to inhabit T cell–rich areas of lymphoid organs, where they function to facilitate interactions between T cells and dendritic cells. However, in vivo manipulation of FRCs has been limited by a dearth of genetic tools that target this lineage. Here, using a mouse model to conditionally ablate FRCs, we demonstrated their indispensable role in antiviral T cell responses. Unexpectedly, loss of FRCs also attenuated humoral immunity due to impaired B cell viability and follicular organization. Follicle-resident FRCs established a favorable niche for B lymphocytes via production of the cytokine BAFF. Thus, our study indicates that adaptive immunity requires an intact FRC network and identifies a subset of FRCs that control B cell homeostasis and follicle identity.

Influence of pupil dilation on retinal nerve fibre layer measurements with spectral domain OCT

PURPOSE

To evaluate the influence of pupil dilation on retinal nerve fibre layer (RNFL) measurements with spectral domain optical coherence tomography (OCT).

PATIENTS AND METHODS

In total, 29 healthy individuals and 26 glaucoma patients underwent RNFL measurements with the Cirrus HD-OCT Model 4000 (Carl Zeiss Meditec Inc.) before and 30-40 min after pupil dilation with one drop of tropicamide 1%. Average thickness, quadrant thickness, and clock-hour thickness measurements were compared with the paired Student's t-test. We also compared the quality scores of the images obtained pre- and post-pupil dilation.

RESULTS

Mean ages in the glaucoma and control groups were 58.3+/-13.4 and 41.6+/-16.4 years respectively (P<0.001). Mean deviation values were -6.96+6.31 dB in the glaucoma group and -1.26+0.79 dB in the control group (P<0.001). Mean RNFL measurements obtained in the glaucoma group were significantly lower than those obtained in the control group (P<0.001). There were no statistically significant differences between mean quality scores obtained before and after dilation neither in the glaucoma group (7.73+/-0.92 vs 7.54+/-1.10, P=0.232) nor in the control group (8.14+/-0.88 vs 8.00+/-0.71, P=0.380). There was no statistically significant difference between mean RNFL measurements obtained pre- and post-pupil dilation neither among normal individuals (P>0.05), nor among glaucoma patients (P>0.05).

CONCLUSION

The results of this study indicate that RNFL measurements obtained with spectral domain OCT are not influenced by pupil size.

Hyperglycaemia increases dipeptidyl peptidase IV activity in diabetes mellitus

AIMS/HYPOTHESES

Chronic hyperglycaemia increases dipeptidyl peptidase IV (DPP-IV) activity in endothelial cells in vitro. The present study was designed to assess the effect of high glucose on circulating DPP-IV activity in patients with type 1 and type 2 diabetes.

METHODS

Plasma DPP-IV activity was measured in 29 patients with type 1 diabetes and 29 age-, sex- and BMI-matched control subjects. We also assessed DPP-IV activity in 31 type 2 diabetic patients with HbA1c > 8.5% and in plasma from matched groups of 31 newly diagnosed diabetic subjects with HbA1c < 7.5%, 31 subjects with IGT and 62 subjects with NGT. In a further sample of 66 type 2 diabetic patients, a longitudinal study was also performed to evaluate variations in DPP-IV activity and HbA1c over 3 months.

RESULTS

DPP-IV activity in type 1 diabetic patients was not significantly different from that in control subjects; however, a significant correlation between DPP-IV and HbA1c was observed in diabetic subjects (r = 0.47; p < 0.01). Type 2 diabetic patients with HbA1c > 8.5% showed significantly (p < 0.05) higher DPP-IV activity (mean+/-SD 27.7+/-7.1 U/l) than newly diagnosed diabetic patients and subjects with IGT (22.1+/-6.0 and 18.8+/-8.8 U/l, respectively). Variations in DPP-IV activity over 3 months in type 2 diabetic patients showed a significant positive correlation with variations in HbA1c (r = 0.26; p < 0.05).

CONCLUSIONS/INTERPRETATION

Chronic hyperglycaemia induces a significant increase in DPP-IV activity in type 1 and type 2 diabetes. This phenomenon could contribute to the reduction in circulating active glucagon-like peptide-1 and to the consequent postprandial hyperglycaemia in type 2 diabetic patients with poor metabolic control.

Effects of metformin on glucagon-like peptide-1 levels in obese patients with and without Type 2 diabetes

Metformin has been shown to increase glucagon-like peptide-1 (GLP-1) levels after an oral glucose load in obese non-diabetic subjects. In order to verify if this effect of the drug was also present in obese Type 2 diabetic patients who have never been treated with hypoglycemic drugs, 22 Type 2 diabetic and 12 matched non-diabetic obese patients were studied. GLP-1 was measured before and after a 100 g glucose load at baseline, after a single oral dose of 850 mg of metformin, and after 4 weeks of treatment with metformin 850 mg three times daily. Post-load GLP-1 levels were significantly lower in diabetic patients. A single dose of metformin did not modify GLP-1 levels. After 4 weeks of treatment, fasting GLP-1 increased in diabetic patients (3.8 vs 4.9 pmol/l; p<0.05), while the incremental area under the curve of GLP-1 significantly increased in both diabetic [93.6 (45.6-163.2) vs 151.2 (36.0-300.5) pmol x min/l; p<0.05] and non-diabetic [187.2 (149.4-571.8) vs 324.0 (238.2-744.0) pmol x min/l; p<0.05] subjects. In conclusion, GLP-1 levels after an oral glucose load in obese type 2 diabetic patients were increased by 4 weeks of metformin treatment in a similar fashion as in obese subjects with normal glucose tolerance.

Fasting plasma glucose and glycated haemoglobin in the screening of diabetes and impaired glucose tolerance

The use of fasting plasma glucose (FPG) only has been proposed for the screening and diagnosis of diabetes, but its sensitivity has been reported to be unsatisfactory. The use of HbA1C, alone or combined with FPG, has been suggested for the screening of diabetes and impaired glucose tolerance (IGT). In a sample of 1215 adult subjects without previously known diabetes, we assessed the sensitivity and specificity of FPG and HbA1C in diagnosing diabetes and IGT, determined by oral glucose tolerance test (OGTT). All lean diabetic patients, and 85% of overweight and obese diabetic individuals, had FPG > or =7 mmol/l. FPG >6.1 mmol/l had a sensitivity of 98.8% and a specificity of 32.9%; HbA1C had a lower specificity and sensitivity for the screening of diabetes. A screening strategy for diabetes based on FPG, with OGTT in all overweight subjects with FPG >6.1 mmol/l, is suggested. Neither FPG nor HbA1C is effective in the screening of IGT; although combined FPG and HbA1C could be useful for case finding, screening for IGT with OGTT is advisable in all subjects at high risk.

Effect of metformin on glucagon-like peptide 1 (GLP-1) and leptin levels in obese nondiabetic subjects

OBJECTIVE

To evaluate the effects of metformin on glucagon-like peptide 1 (GLP-1) and leptin levels.

RESEARCH DESIGN AND METHODS

A total of 10 obese nondiabetic male patients were studied before and after a 14-day treatment with 2,550 mg/day metformin and were compared with 10 untreated obese control subjects. On days 0 and 15, leptin and GLP-1(7-36)amide/(7-37) levels were assessed before and after an oral glucose load during a euglycemic hyperinsulinemic clamp to avoid the interference of variations of insulinemia and glycemia on GLP-1 and leptin secretion. The effects of metformin on GLP-1(7-36)amide degradation in human plasma and in a buffer solution containing dipeptidyl peptidase IV (DPP-IV) were also studied.

RESULTS

Leptin levels were not affected by the oral glucose load, and they were not modified after metformin treatment. Metformin induced a significant (P < 0.05) increase of GLP-1(7-36)amide/(7-37) at 30 and 60 min after the oral glucose load (63.8 +/- 29.0 vs. 50.3 +/- 15.6 pmol/l and 75.8 +/- 35.4 vs. 46.9 +/- 20.0 pmol/l, respectively), without affecting baseline GLP-1 levels. No variations of GLP-1 levels were observed in the control group. In pooled human plasma, metformin (0.1-0.5 microg/ml) significantly inhibited degradation of GLP-1(7-36)amide after a 30-min incubation at 37 degrees C; similar results were obtained in a buffer solution containing DPP-IV.

CONCLUSIONS

Metformin significantly increases GLP-1 levels after an oral glucose load in obese nondiabetic subjects; this effect could be due to an inhibition of GLP-1 degradation.

Glucagon-like peptide (GLP)-1 and leptin concentrations in obese patients with Type 2 diabetes mellitus

AIMS

To assess differences in circulating leptin and glucagon-like peptide (GLP)-1 concentrations before and after an oral glucose load, in euglycaemic and isoinsulinaemic conditions, between obese patients with and without Type 2 diabetes mellitus.

METHODS

Ten male obese (body mass index (BMI) > 30 kg/m2) patients with Type 2 diabetes and 20 matched non-diabetic subjects were studied. Leptin, GLP-1(7-36)amide and GLP-1(7-37) concentrations were measured 0, 30, 60, and 90 min after a 50-g oral glucose load administered 90 min after the beginning of a euglycaemic hyperinsulinaemic clamp.

RESULTS

GLP-1(7-36)amide concentrations before the glucose load were significantly lower in diabetic patients than in controls (median (quartiles): 50.5 (44.7-53.2) vs. 128.7(100-172.5) pg/ml; P < 0.01), while no difference was observed in baseline GLP-1(7-37). In non-diabetic subjects, GLP-1(7-36)amide and GLP-1(7-37) concentrations increased significantly after the oral glucose load, while no glucose-induced increase in GLP-1 concentration was observed in diabetic patients. GLP-1(7-36)amide at 30, 60, and 90 min, and GLP-1(7-37) at 30 min, of the glucose challenge, were significantly lower in diabetic patients. Leptin concentrations were not significantly different in diabetic patients when compared to non-diabetic subjects, and they did not change after the oral glucose load.

DISCUSSION

Leptin concentrations are not significantly modified in obese Type 2 diabetic patients. GLP-1(7-36)amide baseline concentrations are reduced in Type 2 diabetes; moreover, diabetic subjects show an impaired response of GLP-1 to oral glucose in euglycaemic, isoinsulinaemic conditions. This impairment, which is not the result of differences in glycaemia or insulinaemia during assessment, could contribute to the pathogenesis of hyperglycaemia in Type 2 diabetes mellitus.

Relationship between leptin and oestrogens in healthy women

OBJECTIVE

Leptin. a protein secreted by white adipocytes, plays a relevant role in the regulation of body weight and food intake. A possible role for sex hormones in the regulation of leptin secretion has been suggested; however, the effect of variations in oestrogen concentration on serum leptin levels has not been described so far.

METHODS

In study 1, serum leptin concentrations were measured on days 3, 10, 17 and 24 of the menstrual cycle in 18 healthy, lean, regularly menstruating women, aged 18-35 years. Serum oestradiol, progesterone, testosterone. Delta4-androstenedione, dehydroepiandrosterone sulphate (DHEAS). LH and FSH concentrations were also determined. In study 2, serum leptin and oestradiol levels were measured on the 5th and 7th day of ovarian stimulation with human FSH (225 IU daily) during an in vitro fertilisation programme for infertility in 20 women aged 25-45 years.

RESULTS

The results from study 1 show a physiological fluctuation of leptin levels during the menstrual cycle, which has not been described previously. Leptin levels are significantly lower in the early follicular phase. The results of study 2 show a parallel increase in serum oestrogen and leptin concentrations during FSH administration.

CONCLUSIONS

The fluctuation in leptin levels during the menstrual cycle observed in study 1 is compatible with the hypothesis of a stimulatory effect of oestrogen on leptin secretion. The results of study 2 support the hypothesis of a relevant role for oestrogen in the regulation of leptin secretion. Leptin fluctuations during the menstrual cycle are consistent with reported perimenstrual variations in food craving and consumption.